Rivets are permanent fasteners that join materials by means of a mechanical interlock. They consist of a cylindrical shaft with a head at one end and are installed by deforming the unheaded end after insertion. Rivets are commonly used in structural applications such as bridges and aircraft, where a high level of strength is critical. There are different types of rivets, including solid rivets, blind rivets, and tubular rivets. Blind rivets, also known as pop rivets, can be installed from one side of the workpiece, making them ideal for applications where access to both sides is limited.